Routine Versus As-Needed Stress Testing in Asymptomatic Patients With High-Risk Coronary Calcium

Overview

The purpose of the SMART-EXAM (SMart Angioplasty Research Team-Pragmatic Randomized Trial for Comparing Routine versus As-Needed EXercise or Pharmacologic Stress Testing in Asymptomatic Patients with High-Risk Coronary CalciuM) trial is to compare the major adverse cardiovascular events between routine stress testing and as-needed stress testing in asymptomatic patients with high-risk coronary calcium (Agatston Score ≥ 400) without proven ASCVD.

The coronary artery calcium (CAC) scan, a marker of subclinical coronary atherosclerosis, has become popular for individuals at risk for atherosclerotic cardiovascular disease. CAC is strongly associated with atherosclerotic burden and predicts coronary heart disease events and mortality, regardless of their age, sex, race, or atherosclerotic cardiovascular disease (ASCVD) risk. Furthermore, the progression of CAC is associated with an increased risk for future hard and total coronary heart disease events. The use of CAC scoring was associated with significant improvements in the reclassification and discrimination of incident ASCVD. Nevertheless, the current guidelines recommend CAC measurement for selected cases only with borderline or intermediate risk of ASCVD. However, in real-world practice, CAC testing is increasingly being promoted to the public as a means of self-assessment of cardiovascular risk and is widely being used regardless of ASCVD risk. Non-invasive stress testing is often recommended to exclude potentially dangerous coronary artery disease. However, stress testing in asymptomatic individuals has low sensitivity and specificity.9 Although the 2019 Primary Prevention of Cardiovascular Disease Guidelines do not comment on functional or invasive testing in asymptomatic individuals with a high CAC score, the 2009 Appropriate Use Criteria for Cardiac Radionuclide Imaging report gives a level A recommendation for obtaining a stress test in asymptomatic individuals with CAC score ≥400.10 In addition, the 2013 update of the 2009 document also considers stress imaging appropriate for patients with CAC score \>100. However, there have been no large randomized controlled trials or observational studies that have evaluated the utility of functional or invasive testing in asymptomatic individuals free of ASCVD with high CAC scores. Theoretically, early detection and revascularization of ischemia producing lesions in asymptomatic patients with high-risk coronary calcification without proven ASCVD might reduce the future risk of major adverse cardiovascular events.

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